(function (root, factory) {
    if (typeof define === 'function' && define.amd) {
        /*AMD. Register as an anonymous module.
        *define([], factory); */
        define([], factory());
    } else if (typeof module === 'object' && module.exports) {
        /*Node. Does not work with strict CommonJS, but
        // only CommonJS-like environments that support module.exports,
        // like Node.*/
        module.exports = factory();

    } else {
        /*Browser globals (root is window)*/
        root['watermark'] = factory();
    }
}(this, function () {

    /*Just return a value to define the module export.*/
    var watermark = {};

    var forceRemove = false;

    var defaultSettings = {
        watermark_id: 'wm_div_id',          //水印总体的id
        watermark_prefix: 'mask_div_id',    //小水印的id前缀
        watermark_txt: "测试水印",             //水印的内容
        watermark_x: 20,                     //水印起始位置x轴坐标
        watermark_y: 20,                     //水印起始位置Y轴坐标
        watermark_rows: 0,                   //水印行数
        watermark_cols: 0,                   //水印列数
        watermark_x_space: 50,              //水印x轴间隔
        watermark_y_space: 50,               //水印y轴间隔
        watermark_font: '思源黑体',           //水印字体
        watermark_color: 'black',            //水印字体颜色
        watermark_fontsize: '18px',          //水印字体大小
        watermark_alpha: 0.15,               //水印透明度，要求设置在大于等于0.005
        watermark_width: 100,                //水印宽度
        watermark_height: 100,               //水印长度
        watermark_angle: 15,                 //水印倾斜度数
        watermark_parent_width: 0,      //水印的总体宽度（默认值：body的scrollWidth和clientWidth的较大值）
        watermark_parent_height: 0,     //水印的总体高度（默认值：body的scrollHeight和clientHeight的较大值）
        watermark_parent_node: null,     //水印插件挂载的父元素element,不输入则默认挂在body上
        monitor: true,                   //monitor 是否监控， true: 不可删除水印; false: 可删水印。
    };

    const MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;

    //监听dom是否被移除或者改变属性的回调函数
    var domChangeCallback = function (records) {
        if (forceRemove) {
            forceRemove = false;
            return;
        }
        if ((globalSetting && records.length === 1) || records.length === 1 && records[0].removedNodes.length >= 1) {
            loadMark(globalSetting);
        }
    };

    var hasObserver = MutationObserver !== undefined;
    var watermarkDom = hasObserver ? new MutationObserver(domChangeCallback) : null;
    var option = {
        'childList': true,
        'attributes': true,
        'subtree': true,
    };

    /*加载水印*/
    var loadMark = function (settings) {
        /*采用配置项替换默认值，作用类似jquery.extend*/
        if (arguments.length === 1 && typeof arguments[0] === "object") {
            var src = arguments[0] || {};
            for (key in src) {
                if (src[key] && defaultSettings[key] && src[key] === defaultSettings[key]) continue;
                /*veronic: resolution of watermark_angle=0 not in force*/
                else if (src[key] || src[key] === 0) defaultSettings[key] = src[key];
            }
        }

        /*如果元素存在则移除*/
        var watermark_element = document.getElementById(defaultSettings.watermark_id);
        watermark_element && watermark_element.parentNode && watermark_element.parentNode.removeChild(watermark_element);

        /*如果设置水印挂载的父元素的id*/
        var watermark_parent_element = document.getElementById(defaultSettings.watermark_parent_node);
        var watermark_hook_element = watermark_parent_element ? watermark_parent_element : document.body;

        /*获取页面宽度*/
        // var page_width = Math.max(watermark_hook_element.scrollWidth,watermark_hook_element.clientWidth) - defaultSettings.watermark_width/2;
        var page_width = Math.max(watermark_hook_element.scrollWidth, watermark_hook_element.clientWidth);
        /*获取页面最大长度*/
        // var page_height = Math.max(watermark_hook_element.scrollHeight,watermark_hook_element.clientHeight,document.documentElement.clientHeight)-defaultSettings.watermark_height/2;
        var page_height = Math.max(watermark_hook_element.scrollHeight, watermark_hook_element.clientHeight);

        var setting = arguments[0] || {};
        var parentEle = watermark_hook_element;

        var page_offsetTop = 0;
        var page_offsetLeft = 0;
        if (setting.watermark_parent_width || setting.watermark_parent_height) {
            /*指定父元素同时指定了宽或高*/
            if (parentEle) {
                page_offsetTop = parentEle.offsetTop || 0;
                page_offsetLeft = parentEle.offsetLeft || 0;
                defaultSettings.watermark_x = defaultSettings.watermark_x + page_offsetLeft;
                defaultSettings.watermark_y = defaultSettings.watermark_y + page_offsetTop;
            }
        } else {
            if (parentEle) {
                page_offsetTop = parentEle.offsetTop || 0;
                page_offsetLeft = parentEle.offsetLeft || 0;
            }
        }

        /*创建水印外壳div*/
        var otdiv = document.getElementById(defaultSettings.watermark_id);
        var shadowRoot = null;

        if (!otdiv) {
            otdiv = document.createElement('div');
            /*创建shadow dom*/
            otdiv.id = defaultSettings.watermark_id;
            otdiv.setAttribute('style', 'pointer-events: none !important; display: block !important; ');
            /*判断浏览器是否支持attachShadow方法*/
            if (typeof otdiv.attachShadow === 'function') {
                /* createShadowRoot Deprecated. Not for use in new websites. Use attachShadow*/
                shadowRoot = otdiv.attachShadow({mode: 'open'});
            } else {
                shadowRoot = otdiv;
            }
            /*将shadow dom随机插入body内的任意位置*/
            var nodeList = watermark_hook_element.children;
            var index = Math.floor(Math.random() * (nodeList.length - 1));
            if (nodeList[index]) {
                watermark_hook_element.insertBefore(otdiv, nodeList[index]);
            } else {
                watermark_hook_element.appendChild(otdiv);
            }
        } else if (otdiv.shadowRoot) {
            shadowRoot = otdiv.shadowRoot;
        }

        /* 计算偏移是否超出边距 */
        var rotate = function (x, y, centerX, centerY, deg) {
            var angle = deg * Math.PI / 180;
            var tx = x - centerX;
            var ty = y - centerY;
            var rx = Math.cos(angle) * tx - Math.sin(angle) * ty;
            var ry = Math.sin(angle) * tx + Math.cos(angle) * ty;
            return [rx + centerX, ry + centerY];
        };
        var arr = rotate(0, defaultSettings.watermark_height, defaultSettings.watermark_width / 2, defaultSettings.watermark_height / 2, -defaultSettings.watermark_angle);
        var tempX = Math.ceil(Math.abs(arr[0]));
        var tempY = Math.ceil(Math.abs(arr[1]) - defaultSettings.watermark_height);
        if (defaultSettings.watermark_x_space/2 < tempX) {
            defaultSettings.watermark_x_space = tempX;
        }
        if (defaultSettings.watermark_y_space / 2 < tempY) {
            defaultSettings.watermark_y_space = tempY;
        }

        /*三种情况下会重新计算水印列数和x方向水印间隔：1、水印列数设置为0，2、水印宽度大于页面宽度，3、水印宽度小于于页面宽度*/
        defaultSettings.watermark_cols = parseInt((page_width - defaultSettings.watermark_x) / (defaultSettings.watermark_width + defaultSettings.watermark_x_space));
        var temp_watermark_x_space = parseInt((page_width - defaultSettings.watermark_x - defaultSettings.watermark_width * defaultSettings.watermark_cols) / (defaultSettings.watermark_cols));
        defaultSettings.watermark_x_space = temp_watermark_x_space ? defaultSettings.watermark_x_space : temp_watermark_x_space;
        var allWatermarkWidth;

        /*三种情况下会重新计算水印行数和y方向水印间隔：1、水印行数设置为0，2、水印长度大于页面长度，3、水印长度小于于页面长度*/
        defaultSettings.watermark_rows = parseInt((page_height - defaultSettings.watermark_y) / (defaultSettings.watermark_height + defaultSettings.watermark_y_space));
        var temp_watermark_y_space = parseInt((page_height - defaultSettings.watermark_y - defaultSettings.watermark_height * defaultSettings.watermark_rows) / (defaultSettings.watermark_rows));
        defaultSettings.watermark_y_space = temp_watermark_y_space ? defaultSettings.watermark_y_space : temp_watermark_y_space;
        var allWatermarkHeight;

        if (watermark_parent_element) {
            allWatermarkWidth = defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1);
            allWatermarkHeight = defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1);
        } else {
            allWatermarkWidth = page_offsetLeft + defaultSettings.watermark_x + defaultSettings.watermark_width * defaultSettings.watermark_cols + defaultSettings.watermark_x_space * (defaultSettings.watermark_cols - 1);
            allWatermarkHeight = page_offsetTop + defaultSettings.watermark_y + defaultSettings.watermark_height * defaultSettings.watermark_rows + defaultSettings.watermark_y_space * (defaultSettings.watermark_rows - 1);
        }

        var x;
        var y;
        for (var i = 0; i < defaultSettings.watermark_rows; i++) {
            if (watermark_parent_element) {
                y = page_offsetTop + defaultSettings.watermark_y + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
            } else {
                y = defaultSettings.watermark_y + (page_height - allWatermarkHeight) / 2 + (defaultSettings.watermark_y_space + defaultSettings.watermark_height) * i;
            }
            for (var j = 0; j < defaultSettings.watermark_cols; j++) {
                if (watermark_parent_element) {
                    x = page_offsetLeft + defaultSettings.watermark_x + (page_width - allWatermarkWidth) / 2 + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;
                } else {
                    x = defaultSettings.watermark_x + (page_width - allWatermarkWidth) / 2 + (defaultSettings.watermark_width + defaultSettings.watermark_x_space) * j;
                }
                var mask_div = document.createElement('div');
                var oText = document.createTextNode(defaultSettings.watermark_txt);
                mask_div.appendChild(oText);
                /*设置水印相关属性start*/
                mask_div.id = defaultSettings.watermark_prefix + i + j;
                /*设置水印div倾斜显示*/
                mask_div.style.webkitTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style.MozTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style.msTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style.OTransform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style.transform = "rotate(-" + defaultSettings.watermark_angle + "deg)";
                mask_div.style.visibility = "";
                mask_div.style.position = "absolute";
                /*选不中*/
                mask_div.style.left = x + 'px';
                mask_div.style.top = y + 'px';
                mask_div.style.overflow = "hidden";
                mask_div.style.zIndex = "9999999";
                mask_div.style.opacity = defaultSettings.watermark_alpha;
                mask_div.style.fontSize = defaultSettings.watermark_fontsize;
                mask_div.style.fontFamily = defaultSettings.watermark_font;
                mask_div.style.color = defaultSettings.watermark_color;
                mask_div.style.textAlign = "center";
                mask_div.style.width = defaultSettings.watermark_width + 'px';
                mask_div.style.height = defaultSettings.watermark_height + 'px';
                mask_div.style.display = "block";
                mask_div.style['-ms-user-select'] = "none";
                /*设置水印相关属性end*/
                shadowRoot.appendChild(mask_div);
            }
        }

        // monitor 是否监控， true: 不可删除水印; false: 可删水印。
        const minotor = settings.monitor === undefined ? defaultSettings.monitor : settings.monitor;
        if (minotor && hasObserver) {
            watermarkDom.observe(watermark_hook_element, option);
            watermarkDom.observe(document.getElementById(defaultSettings.watermark_id).shadowRoot, option);
        }
    };

    /*移除水印*/
    var removeMark = function () {
        /*采用配置项替换默认值，作用类似jquery.extend*/
        if (arguments.length === 1 && typeof arguments[0] === "object") {
            var src = arguments[0] || {};
            for (key in src) {
                if (src[key] && defaultSettings[key] && src[key] === defaultSettings[key]) continue;
                /*veronic: resolution of watermark_angle=0 not in force*/
                else if (src[key] || src[key] === 0) defaultSettings[key] = src[key];
            }
        }

        /*移除水印*/
        var watermark_element = document.getElementById(defaultSettings.watermark_id);
        var _parentElement = watermark_element.parentNode;
        _parentElement.removeChild(watermark_element);
        // :ambulance: remove()
        // minotor 这个配置有些冗余
        // 如果用 MutationObserver 来监听dom变化防止删除水印
        // remove() 方法里用 MutationObserver 的 disconnect() 解除监听即可
        watermarkDom.disconnect();
    };

    var globalSetting;
    /*初始化水印，添加load和resize事件*/
    watermark.init = function (settings) {
        globalSetting = settings;
        loadMark(settings);
        window.addEventListener('onload', function () {
            loadMark(settings);
        });
        window.addEventListener('resize', function () {
            loadMark(settings);
        });
    };

    /*手动加载水印*/
    watermark.load = function (settings) {
        globalSetting = settings;
        loadMark(settings);
    };

    /*手动移除水印*/
    watermark.remove = function () {
        forceRemove = true;
        removeMark();
    };


    //监听dom是否被移除或者改变属性的回调函数
    var callback = function (records) {
        if ((globalSetting && records.length === 1) || records.length === 1 && records[0].removedNodes.length >= 1) {
            loadMark(globalSetting);
            return;
        }

        // 监听父节点的尺寸是否发生了变化, 如果发生改变, 则进行重新绘制
        var watermark_parent_element = document.getElementById(defaultSettings.watermark_parent_node);
        if (watermark_parent_element) {
            var newWidth = getComputedStyle(watermark_parent_element).getPropertyValue('width');
            var newHeight = getComputedStyle(watermark_parent_element).getPropertyValue('height');
            if (newWidth !== recordOldValue.width || newHeight !== recordOldValue.height) {
                recordOldValue.width = newWidth;
                recordOldValue.height = newHeight;
                loadMark(globalSetting);
            }
        }
    };
    // const MutationObserver = window.MutationObserver || window.WebKitMutationObserver || window.MozMutationObserver;
    var watermarkDom = new MutationObserver(callback);
    var option = {
        'childList': true,
        'attributes': true,
        'subtree': true,
        'attributeFilter': ['style'],
        'attributeOldValue': true
    };
    var recordOldValue = {
        width: 0,
        height: 0
    }

    return watermark;
}));
